1. Field of the Invention (Technical Field)
The present invention relates to extended range image processing, particularly of image data acquired via Electro-Optical (EO) systems.
2. Description of Related Art
The present invention relates to extended range (XR™) image processing of image data acquired via EO systems, as described in references such as: (1) U.S. patent application Ser. No. 09/840,920, entitled “Scene-based non-uniformity correction for detector arrays”, filed Apr. 25, 2001, and published as Publication No. 2002/0159101 on Oct. 31, 2002; (2) U.S. patent application Ser. No. 09/841,081, entitled “Dynamic range compression”, filed Apr. 25, 2001, and published as Publication No. 2002/0159648 on Oct. 31, 2002; (3) U.S. patent application Ser. No. 09/841,079, entitled “Extended range image processing for electro-optical systems”, filed Apr. 25, 2001, and published as Publication No. 2002/0159651 on Oct. 31, 2002; and (4) U.S. patent application Ser. No. 10/125,348, entitled “Scene-based non-uniformity offset correction for staring arrays”, filed Apr. 19, 2002, and published as Publication No. 2003/0198400 on Oct. 23, 2003.
One technique for addressing the range performance and Nyquist frequency limitations of an EO system is to dither the system, such that the system will sample once, then move the sensor over some sub-pixel amount, and then sample again. Such a technique gives the EO system the appearance that the image is sampled twice as often, and, therefore, the Nyquist frequency of the sensor has effectively doubled. This is often implemented using a dither mechanism such as a Fast Scan Mirror (FSM). However, dither mechanisms, such as a FSM, are usually very expensive and are sensitive to vibrations and alignment. Previous implementations also have comprised rotating cube prisms or oscillating plates which provide linear rather than rotary scans. Two mechanisms with separate tilted optical plates or prisms are required for orthogonal linear motion.
The present invention employs a property of a tilted plane parallel plate used in a converging beam of an imaging system, namely that of deviating the line of sight of the image. The invention uses a rotating motion of the tilted plate along an axis parallel to the line of sight to provide a continuously rotating deviation or dither to the image. The line of sight moves in two axes with a single mechanism.